Warren Buffett wrote this article, originally titled “America’s Growing Trade Deficit Is Selling The Nation Out From Under Us. Here’s A Way To Fix The Problem–And We Need To Do It Now” for Fortune in November 2003. At the time, few were talking about free trade as an issue. But free trade and whether it harms or helps the U.S. economy and U.S. workers has become a major policy debate in the current presidential election cycle. In the article, Buffett proposes a novel trade system that is nonetheless along the lines of what Donald Trump and Bernie Sanders have proposed. Reached recently by Fortune by email, Buffett says that he still mostly believes in what he wrote in the pages of our magazine 13 years ago, “though the problem has diminished a bit because of the lower price of oil and our country's increased reliance on domestic production."

I’m about to deliver a warning regarding the U.S. trade deficit and also suggest a remedy for the problem. But first I need to mention two reasons you might want to be skeptical about what I say. To begin, my forecasting record with respect to macroeconomics is far from inspiring. For example, over the past two decades I was excessively fearful of inflation. More to the point at hand, I started way back in 1987 to publicly worry about our mounting trade deficits–and, as you know, we’ve not only survived but also thrived. So on the trade front, score at least one “wolf” for me. Nevertheless, I am crying wolf again and this time backing it with Berkshire Hathaway’s money. Through the spring of 2002, I had lived nearly 72 years without purchasing a foreign currency. Since then Berkshire has made significant investments in–and today holds–several currencies. I won’t give you particulars; in fact, it is largely irrelevant which currencies they are. What does matter is the underlying point: To hold other currencies is to believe that the dollar will decline.

Both as an American and as an investor, I actually hope these commitments prove to be a mistake. Any profits Berkshire might make from currency trading would pale against the losses the company and our shareholders, in other aspects of their lives, would incur from a plunging dollar.

But as head of Berkshire Hathaway, I am in charge of investing its money in ways that make sense. And my reason for finally putting my money where my mouth has been so long is that our trade deficit has greatly worsened, to the point that our country’s “net worth,” so to speak, is now being transferred abroad at an alarming rate.

A perpetuation of this transfer will lead to major trouble. To understand why, take a wildly fanciful trip with me to two isolated, side-by-side islands of equal size, Squanderville and Thriftville. Land is the only capital asset on these islands, and their communities are primitive, needing only food and producing only food. Working eight hours a day, in fact, each inhabitant can produce enough food to sustain himself or herself. And for a long time that’s how things go along. On each island everybody works the prescribed eight hours a day, which means that each society is self-sufficient.

Eventually, though, the industrious citizens of Thriftville decide to do some serious saving and investing, and they start to work 16 hours a day. In this mode they continue to live off the food they produce in eight hours of work but begin exporting an equal amount to their one and only trading outlet, Squanderville.

The citizens of Squanderville are ecstatic about this turn of events, since they can now live their lives free from toil but eat as well as ever. Oh, yes, there’s a quid pro quo–but to the Squanders, it seems harmless: All that the Thrifts want in exchange for their food is Squanderbonds (which are denominated, naturally, in Squanderbucks).

Over time Thriftville accumulates an enormous amount of these bonds, which at their core represent claim checks on the future output of Squanderville. A few pundits in Squanderville smell trouble coming. They foresee that for the Squanders both to eat and to pay off–or simply service–the debt they’re piling up will eventually require them to work more than eight hours a day. But the residents of Squanderville are in no mood to listen to such doomsaying.

Meanwhile, the citizens of Thriftville begin to get nervous. Just how good, they ask, are the IOUs of a shiftless island? So the Thrifts change strategy: Though they continue to hold some bonds, they sell most of them to Squanderville residents for Squanderbucks and use the proceeds to buy Squanderville land. And eventually the Thrifts own all of Squanderville.

At that point, the Squanders are forced to deal with an ugly equation: They must now not only return to working eight hours a day in order to eat–they have nothing left to trade–but must also work additional hours to service their debt and pay Thriftville rent on the land so imprudently sold. In effect, Squanderville has been colonized by purchase rather than conquest.